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When misalignment between a motor shaft and a driven component causes vibration, noise, or premature wear, the right flexible shaft coupling makes all the difference. The D25 Parallel Slit Flexible Shaft Coupling is engineered for CNC machine builders, robotics integrators, and motion control engineers who need reliable torque transmission with built-in compensation for angular and parallel misalignment — without sacrificing rotational accuracy.
This coupler features an aluminum alloy body with a parallel slit (beam) cut pattern, giving it the flexibility to absorb minor shaft misalignment while maintaining zero-backlash torque transfer. The outer diameter is 25mm (≈0.98 in) and the body length is 30mm (≈1.18 in). Bore sizes (φd1 × φd2) range from 6mm to 14mm on each side, covering a wide range of motor and encoder shaft combinations. Set screws secure each bore independently for a firm, slip-free grip.
Typical applications include CNC router and milling machine Z-axis lead screw connections, servo motor-to-encoder shaft coupling in closed-loop motion systems, stepper motor drive shaft connections in 3D printers and laser engravers, and rotary encoder mounting in industrial automation panels. The compact D25 form factor fits tight machine envelopes where larger jaw or disc couplings cannot.
The parallel slit cut pattern provides torsional flexibility while eliminating rotational play, making it suitable for closed-loop servo and encoder applications where positional accuracy is critical.
Available in φd1 × φd2 combinations from 6mm to 14mm on each side — including both equal and mixed bore sizes — to match a broad range of motor shaft and encoder shaft diameters in a single coupler.
Lightweight yet rigid aluminum alloy construction keeps rotational inertia low, reducing load on servo motors and improving dynamic response in high-cycle CNC and automation applications.
Each bore side is secured by its own set screw, allowing independent tightening and ensuring a firm, concentric grip on shafts of different diameters without distorting the coupler body.
Available in Pack of 1, Pack of 3, or Pack of 5 — ideal whether you need a single replacement coupler or a batch for a multi-axis machine build or production run.
At 25mm OD × 30mm length, this coupler fits tight machine envelopes on desktop CNC routers, compact laser engravers, and small-format 3D printers where space around the motor mount is limited.
| Outer Diameter (D) | 25mm (≈0.98 in) |
|---|---|
| Body Length (L) | 30mm (≈1.18 in) |
| Bore Diameter φd1 | See variant options (6–14mm) |
| Bore Diameter φd2 | See variant options (6–14mm) |
| Coupling Type | Parallel Slit (Beam) Flexible |
| Material | Aluminum Alloy |
| Finish | Natural anodized / machined |
| Clamping Method | Set screw (per bore side) |
| Backlash | Zero backlash |
| Misalignment Compensation | Angular and parallel |
| Pack Quantity | See variant options (1 / 3 / 5 pcs) |
Measure the shaft diameter on your motor side and your driven component side (encoder, lead screw, etc.) using a caliper. Select the variant where φd1 matches your motor shaft and φd2 matches your driven shaft. If both shafts are the same diameter, choose an equal-bore variant (e.g., 8mm × 8mm). Mixed-bore variants (e.g., 6mm × 10mm) are available for mismatched shaft pairs.
Yes — the parallel slit design transmits torque through the elastic deformation of the aluminum body rather than through interlocking teeth or elastomeric inserts, so there is no mechanical play between the two bores. Over time, ensure set screws remain tight; a loose set screw is the most common cause of apparent backlash in slit couplings.
Exact rated torque and RPM depend on the specific bore size and operating conditions. For a D25 aluminum parallel slit coupling of this size, typical rated torque is in the range of 1–3 N·m and operating speeds up to 3,000–5,000 RPM are common. Contact us to confirm specifications for your specific application before ordering for high-load or high-speed use.
The aluminum alloy body offers good resistance to oxidation in typical indoor workshop and light industrial environments. It is not recommended for continuous exposure to cutting fluids, strong acids, or salt spray without additional protective measures. For wet or chemically aggressive environments, consider a stainless steel coupling instead.
Yes — this is one of the most common use cases for this coupler. Select the bore combination that matches your stepper motor shaft diameter (commonly 5mm, 6.35mm, or 8mm) and your lead screw shaft diameter. Note that 5mm bore is not available in this D25 series; the minimum bore is 6mm. If your motor shaft is 5mm, you may need a different coupler series.
All packs contain the same coupler in your chosen bore size combination. Pack of 1 is ideal for a single-axis build or replacement. Pack of 3 suits a 3-axis CNC machine (X, Y, Z). Pack of 5 is cost-effective for multi-machine builds, production batches, or keeping spares on hand. Pricing scales accordingly.
Insert each shaft fully into its respective bore until it reaches the center of the coupler body. Use an appropriate hex key (Allen wrench) to tighten the set screw on each side firmly against the shaft flat or shaft surface. For shafts without a flat, apply thread-locking compound to the set screw threads to prevent loosening under vibration. Do not overtighten, as this can deform the slit pattern and reduce flexibility.
